1. Field of the Invention
This invention relates to a drive for rotatable cutter mechanisms and more particularly to a drive for a pair of rotatable cutter mechanisms arranged to cut different length notches in a moving web.
2. Description of the Prior Art
Rotating blade type cutting mechanisms for cutting notches in a moving web are known. British Patent 850,797 entitled "Improvements In Or Relating To Apparatus For Slotting The Edges Of Running Webs" discloses a cutting mechanism that includes a pair of rotatable cutting knives that are separately driven by means of meshing gears connected to a common drive shaft. The cutting sequence of the pair of tandem knives is adjusted by adjusting the relative position of the cutting knives to the drive gears.
U.S. Pat. No. 3,782,233 discloses a rotatable cutter mechanism that includes pairs of rotatable cutting knives positioned on opposite sides of the web and arranged to cut different length notches in the moving web material. The cutting knives are non-rotatably secured to rotatable shafts mounted on a platform that are, in turn, connected through coupling devices to gear boxes which, in turn, are connected to a common drive shaft.
German OLS 1,769,688 entitled "Cutting Arrangement For Envelope And Bag Machines" also discloses apparatus for cutting notches in the sides of an endless web.
The known rotating blade type cutters are all mechanically connected to a common drive shaft so that it is not possible to adjust the phase register between the cutting operation of the knives and the relative position of the web while the web is moving and with the direct mechanical connections substantial backlash is present that limits the accuracy of the notches cut in the side edges of the web.
There is a need for a drive mechanism that is associated with rotatable cutter mechanisms that can adjust phase register between the knives and the web while the cutter mechanism is in operation. There is also a need for apparatus to reduce the backlash to provide more accurate phase register during operation of the cutting mechanism and provide for a quicker size change.